The invention relates to a constant velocity universal ball joint consisting, of an outer joint part with outer ball tracks, an inner joint part with inner ball tracks, torque transmitting balls guided in pairs of tracks formed of one outer ball track and one inner ball track, an annular ball cage held between the outer joint part and the inner joint part and having circumferentially distributed cage windows each receiving one of the balls, the ball cage forms an inner face which is internally widened between two end apertures of the ball cage, the inner joint part comprises a greatest outer diameter which is greater than each of the inner diameters of the end apertures of the ball cage.
With joints of this type, the outer diameter of the inner joint part (ball hub) is greater than the end apertures of the annular ball cage, between which end apertures there extends the widened inner face. The inner face of the bail cage, in this case, is in contact via annular faces with the outer face of the inner joint part, which outer face is formed of individual webs. To be able to insert the inner joint part into the ball cage under these conditions, it is possible to provide the ball cage with notches at the end aperture of the cage through which the inner joint part with the webs is coaxially introduced into the ball cage in a rotational position which is functionally incorrect, whereupon the inner joint part and the ball cage are rotated relative to one another by half the dimension of the window pitch into a functionally accurate position. The length of the webs can be greater than the circumferential extension of the cage windows. As a result of this design, the strength of the ball cage is reduced.
In the case of other joints it is possible for the inner joint part to be inserted into the ball cage through an end aperture of same, with intersecting axes, in such a way that one of the webs of the inner joint part engages one of the cage windows from the inside, and the radially opposite web of the inner joint part can subsequently be introduced through the same end aperture into the cage interior. After the inner joint part has reached its central position in the ball cage, the parts are rotated relative to one another in such a way that their axes coincide. This presupposes that the axial extension of at least one of the webs is shorter than the circumferential extension of the cage windows. Said limitation of the web length restricts the ball guidance in the inner joint part.
With reference to constant velocity fixed ball joints wherein the length of the webs at the inner joint part exceeds the circumferential extension of the cage windows, i.e. in particular with joints with a large number of balls, it is the object of the invention to provide a design which avoids a loss of strength at the cage.
The objective is achieved by combining the following characteristics:
adjoining inner ball tracks of the inner joint part form webs whose axial length is greater than the circumferential extension of the cage windows of the ball cage, the ball cage can be elastically ovalised to the extent that, when the axes of the ball cage and of the inner joint part intersect one another approximately perpendicularly upon contact between a web of the inner joint part and the inner face of the ball cage, the opposed web of the inner joint part is able to pass through an end aperture.
The means described here allow the provision of joints which, due to relatively small, circular end apertures of identical size at the ball cage, do not suffer from any adverse effects on the cage strength and wherein, in addition, due to the un-reduced length of the webs, ball guidance and the transmission of torque are ensured, even at large articulation angles.
According to a further embodiment it is proposed that the ball cage can be elastically ovalised to the extent that, when the axes of the ball cage and of the inner joint part intersect one another approximately perpendicularly, the inner joint part is able, via the smallest side projection, to pass through an end aperture of the ball cage.
According to yet a further embodiment it is proposed that the ball cage can be elastically ovalised to such an extent that, when the axes of the ball cage and of the inner joint part intersect one another approximately perpendicularly, the inner joint part is able, via the greatest diameter, to pass through the end aperture of the ball cage.
Both the above-mentioned embodiments require a greater deformation of the ball cage, but permit more freedom in respect of assembly sequences, which can be advantageous as far as automation is concerned.
According to a special embodiment it is proposed that a longitudinally extending deepened groove has been worked into the track base of at least one inner ball track of the inner joint part. Furthermore, it is proposed that a centrally circumferentially extending deepened groove has been worked into the inner face of the ball cage. Furthermore, it is conceivable that, at least in a widened end portion of an inner ball track of the inner joint part, there has been worked in a notch which extends centrally relative to the longitudinal extension of the track. With the help of said measures the extent of ovalisation of the ball cage required for mounting the cage can be reduced in that there is achieved a deeper engagement between the inner edge of the end aperture of the cage and the inner ball track of the inner joint part.
The solution in accordance with the invention is particularly suitable for joints with counter tracks wherein pairs of tracks of first outer ball tracks and of first inner ball tracks open in a first axial direction and wherein pairs of tracks of second outer ball track and of second inner ball tracks open in the second opposed axial direction. These joints will primarily be fixed joints wherein inner annular faces of the inner face of the ball cage are in a centring contact with outer faces of the inner joint part.